1. Field of the Invention
The present invention relates to an airbag system to protect vehicle occupants in the event of a side impact and the like.
2. Description of Relevant Art
A head-protecting system has been known as an airbag system to protect vehicle occupants in the event of a side impact, a rolling over, and the like. This type of airbag system expands the airbag from a roof side rail portion for covering a side window to protect a head of occupant. The head-protecting system expands the airbag downwardly along a side door so as to cover a small space between an occupant and a side door. Accordingly, the head-protecting system has to expand the airbag faster than the front impact-airbag system, which expands the airbag into a large space such as between an occupant and the steering wheel, or between an occupant and the dashboard. Furthermore, the head-protecting system has to expand the airbag into a large area to protect front and rear occupants.
Accordingly, in this head-protecting system, the airbag is arranged in the vehicle extending from a front pillar to a rear pillar via the roof.
The head-protecting system detects a side impact of the vehicle by the combination of an acceleration sensor and a side acceleration sensor. Herein, the acceleration sensor is placed in an ECU (Electric Control Unit) provided on a front side of a floor, and the side acceleration sensor is provided around a front occupant seat at a side of the vehicle. When these two acceleration sensors detect a side impact, the head-protecting system expands the airbag into the space ranging from a front occupant side to a rear occupant side at a side of a vehicle compartment.
However, when a side impact occurs at a rear occupant side, the side impact will be detected with a little delay, or the impact caused by collision will not be detected and the impact is mitigated, since the acceleration sensor is not near to an area where the vehicle receives the side impact.
Accordingly, there are possibilities such that the head-protecting system can not expand the air bag within an appropriate time, or the head-protecting system can not expand the airbag completely.
Moreover, there are the following drawbacks. When the side impact occurs at a rear occupant side, the airbag dose not have to expand to protect a front occupant due to the fact that the impact caused by collision is mitigated since a front occupant seat is not near to an area where the vehicle receives the side impact. Similarly, When the side impact occurs at a front occupant side, the airbag dose not have to expand to protect the rear occupant due to the fact that the impact caused by the collision is mitigated since a rear occupant seat is not near to the area where the vehicle receives the side impact.
However, the aforementioned head-protecting system expands the airbag from the front occupant seat to the rear occupant seat. This means that the airbag is expanded into also unnecessary space. Additionally, when gas is supplied by one inflator into the airbag for being expanded into over such large space, too much time is required to introduce gas into the airbag for filling completely, at the same time, the inflator needs to be large size too.
Therefore, the object of the present invention is to provide the airbag system capable of expanding the airbag into a required area in appropriate timing in the event of the side impact and the like.